switch ( b ) {
            case "A": a = ValueMapper.A.A;
            break;
            case "B": a = ValueMapper.A.B;
            break;
            default: throw new IllegalArgumentException( "Unexpected enum constant: " + b );
        }

        ValueMapper.A a = switch (b) {
            case "A" -> A.A;
            case "B" -> A.B;
            default -> throw new IllegalArgumentException("Unexpected enum constant: " + b);
        };